Photomasks are an integral part of the lithographic process of semiconductor manufacturing. Photomasks are quartz or glass plates that contain precision images of layers of integrated circuits. They are used to optically transfer the images to semiconductor wafers during photoresist exposure.
Photomasks require complex mathematical algorithms for their design and use sophisticated manufacturing techniques. To make a photomask, a customer, such as a chipmaker, provides the photomask manufacturer with circuit design data and photomask specifications. This data is used to generate photomask pattern data in a format appropriate for the manufacturing equipment. Each photomask is then created by using photolithographic techniques.
Conventionally, the data provided by the customer is in whatever format is convenient for the customer, based on the customer's design system. The circuit design data is typically from a CAD type system, with a design for each pattern. The data might be delivered to the manufacturer on various media, such as a floppy disk, magnetic tape, cassette, or via a modem connection. The photomask specifications might be in hardcopy form or in electronic form, on some sort of physical media delivered to the manufacturer, or delivered electronically. There is no guarantee that this customer-provided data will be complete or that it will result in a manufacturable photomask.